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    <title>Document</title>
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        #Div {
            width: 100px;
            height: 100px;
            border: 1px solid gold;
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    <!-- a标签不能嵌套a标签 -->
    <a href="http://www.baidu.com" target="_blank">百度<a href="http://www.taobao.com" target="_blank">淘宝</a></a>

    <!-- 可以嵌套 -->
    <a href="http://www.baidu.com" target="_blank">
        <p>Hello</p>
    </a>

    <!-- 可以嵌套 -->
    <a href="http://www.baidu.com" target="_blank">
        <div id="Div">Hello</div>
    </a>

    <!-- 可以嵌套 -->
    <span>
        <a href="http://www.baidu.com" target="_blank">
            <p>Wolrd</p>
        </a>
    </span>
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